Plate and method of treating the same



Sept. 23, 1924. 1,509,496

J. SLEPIAN PLATE AND METHOD OF TREATING THE SAME Original Filed April 1, 1.922

nz v 6 L 5% WITNESSES: VENTOR Q I dig (J/epmn. 4 M 2 A-TTORNEY Patented Sept. 23, 1924.

' UNITED :STATES PATENT OFFICE.

JOSEPH SLEIIAN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELATE AND METHOD OF TREATING THE SAME.

Application filed April 1, 1922, Serial No. 548,638. Renewed January 31, 1924.

T all whom it may concern.

Be it known that I, JOSEPH SLEPIAN, a citizen of the United States, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Plates and Methods of Treating the Same, of which the following is a specification.

This invention relates to lightning arresters, more particularly to disk-pile lightning arresters such as are described in my copending application, Serial No. 535,810, filed February 11, 1922.

In the aforesaid application, I have described a lightning arrester consistingessentially of plates or disks of high-resistance material, the surfaces of which are in contact. The plates are actually in contact at only a relatively small number of points and the action of the arrester, in preventing injury to an electrical system, consists in establishing a glow discharge between parts of the plates which are not in actual contact. Owing to the points of contact of the plates, there is a relatively small leakage current which causes a loss of energy at all times.

Although this loss is relatively small, it is desirable that it be avoided as much as possible and I, therefore, prefer to increase the resistance of those parts of the plates which are'in contact. This may be accomplished by providing raised portions of higher resistance on the plates, as is disclosed in my copending application, Serial No. 536.910, filed February 16, 1922.

The present invention is designed to providea high resistance along the area of contact of tie plates, it being among the objects thereof to. provide a plate having such high resistance along the contacting surface thereof as to insure that only a practically negligible leakage current flows therethrough.

It is a further object of my invention to provide a method of treating such plates of high-resistance material as to ensure the above-mentioned result.

In practising my invention, I utilize plates of high-resistance material of any sultable composition and preferably consisting of a mixture of kaolin, carborundum and graphite, in suitable proportions, baked to form a solid plate. To increase the resistance of the surfaces of such plates, I assemble a suitable number thereof in superposed relation, clamp the same together and apply a-direct voltage which is somewhat less than the voltage necessary to produce a glow discharge between said plates, for a very short time. This operation is repeated several times, the total input of energy being kept so low that the plates do not heat up, as a whole. This treatment results in the points of contact of the disks being strongly heated, causing some of the graphite particles to become oxidized, thus increasing the resistance at the points of contact a large number of times.

I have found that, in some cases, the action does not result in a uniform increase in resistance of the contact surfaces and, in order to improve upon my method of treatment of the plates, I have devised the following modification. In assembling the plates of high-resistance material for treatment under high voltage, I place between the plates thin spacers which are not affected by the heat treatment. Generally, I use thin spacers of mica which are less than one mil in thickness.

When a series of plates separated by such thin mica spacers are clamped together, the disks touch at a number of points. The voltage is applied to the stacked disks as before and the contacts are oxidized and the resistance thereof thus increased. Since the pressure holding the plates together is not carried by the relatively small number of contact points, the danger of some of said points being burnt off and yielding under the pressure is eliminated. As a result of this improvement, I have been enabled to greatly increase the contact resistance of plates, for instance, from 400 ohms to 400,000 ohms.

The amount of energy necessary to perform this operation is very small and I have found that a continuous input of from'3 to 5 watts per disk is sufiicient to raise the resistance of plates one inch in diameter and having a specific resistance of 100 ohms per cubic cc. to the desired degree.

In the accompanying drawings constituting a part hereof and in which like reference characters designate like parts,

Fig. 1 is a vertical cross-sectional view of a plurality of plates of high-resistance material clamped in position for treatment, the contact surfaces thereof being greatly magnified; a

Fig. 2 is a similar view showing a modification' of my invention;

Fig. 3 is a plan view of a plate, an

Fig. 4 is a cross-sectional view thereof along the line IVIV. of Fig. 3, the contour of the surfaces thereof being greatly magnified.

A plurality of plates 1 of high-resistance material, preferably but not necessarily containing graphite, carborundum and kaolin, are placed in suplerposed relation, as shown in Fig. 1, meta placed on the ends of the stack and the whole clamped together. Terminal leads 4 and 5 are connected to electrodes 2 and 3, respectively, and serve to conduct the energy used in the process to the plates. A direct-current potential of about 300 volts is applied for a very short time, the energy being cut off and the operation repeated several times a minute for. a suitable length of time. This treatment causes the contact surfaces 6 of the plates to become hot and the. graphite therein becomes .at least partially oxidized, thereby greatly increasing the resistance of the contact points.

In the modification of my invention shown in Fig. 2, I stack the plates 1 with the electrodes 2 and 3 and leads 4 and 5 connected to the same as before, but place between the plates thin washers or spacers 7 of suitable material unaffected by the temperature and character of the treatment, such as mica. The mica spacers do not pevent the surfaces 6 of the plates from coming into contact and the treatment of the plates by means of the voltage applied proceeds as in the case where no spacers are used.

As the result of such treatment of the plates, the faces thereof become of greatly mcreased resistance, and the surfaces of said plates may have resistances as much as a thousand times greater than that of the body portion.

Although I have described my invention, setting forth several embodiments thereof, it is obvious that my invention is not limit? ed to the details shown and described.' For instance, the lates of resistanceTnaterial do 'not'necessari y consist of the ingredients set forth but any suitable resistance material, the resistance of which may be increased by an electrical treatment, may be substituted therefor. Mica separators are not absolutely essential in practising my invention, it being feasible to omit such spacers or to substitute spacers of another material. These and various other changes may be made in my invention without departing from the spirit and scope thereof.

I claim'as my invention:

ic electrodes 2 and 3 are.

1. A plane plate of high-resistance mateing a face thereof of higher resistance than the body portion.

3. A plate of high-resistance material having the opposite faces thereof of higher resistance than the body portion.

4. A method of treating plates of high-resistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact and passing energy .therethrough to heat the contact surfaces of said plates and thus increase the resistance thereof.

5. A method of treating plates of high-- resistance material to increase the resistance of certain parts thereof. which comprises placing a plurality of plates in contact and passing a current therethrough to oxidize the contact surfaces of said plates and thus increase the resistance thereof.

6. A method of treating plates of high-resistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact and passing a direct current therethrough to oxidize the contact surfaces of said plates and thus increase the-resistance thereof.

7. A method of treating plates of high-resistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact, insertin'g thin spacers therebetween. and passing a current therethrough to oxidize the contact surfaces of said plates and thus increase the resistance thereof.

8. A method of treating plates of high-resistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact, inserting thin mica spacers therebetween, and passing a current therethrough to oxidize the contact surfaces of said plates and thus increase the resistance thereof.

9. A method of treating plates of high-resistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact, inserting thin mica spacers of less than one mil thickness therebetween, and passing a current therethrough to oxidize the contact surfaces of said plates and thus increase the resistance thereof.

10. A method of treating plates of highresistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact, clamping the same together, and passing a current therethrough to oxidize the contact surfaces of said plates and thusincrease the resistance thereof.

11. A method of treating plates of highresistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact, inserting thin spacers therebetween, clamping the same together, and passing a current therethrough to oxidize the contact surfaces of said plates and thus increase the resistance thereof.

12. A method of treating plates of highresistance material to increase the resistance of certain parts thereof which comprises placing a plurality of plates in contact and and passing energy therethrough.

15. A method of treating plates of highresistance material to increase the resistance of certain parts thereof which comprises interposing thin spacers between said plates and passing a discharge therethrough.

16. A method of. treating plates of highresistance material to increase the resistance of certain parts thereof which comprises interposing thin spacers between said plates therethrough to oxidize parts of said carbon.

19. A lightning arrester comprising a plurality of plane bodies of high resistance material disposed in contact with each other, the contacting portions of one or more of the bodies having higher specific resistance than the body portion thereof.

30. A lightning arrester comprising a plurality of plane bodies of high resistance material disposed in contact with each other at only a relatively small number of points,

the remaining portions of the contact sur-' faces being spaced, portions of the contact surface of at least one of the bodies being of higher resistance than the body portion.

21..A lightning arrester comprising a plurality of plane bodies of high resistance material disposedin contact with each other, the contacting portions of one or more of the bodies having higher specific resistance than the body portion thereof, the spacing and resistivity being such that the space current flow always takes the form of a glow discharge.

22. A lightning arrester comprising a plurality of plane bodies of high resistance material disposed in contact with each other at only a relatively small number of points, the remaining portions of the contact sur-. faces being spaced, portions of the contact surface of at least one of the bodies being of higher resistance than the body portion, the spacing and resistivity being such that the space current flow always takes the form of a glow discharge.

23. A space-current discharge device comprising electrode plates contacting at only a relatively small number of points, the remaining portions of the contact surfaces being spaced, at least one of said plates being aplane plateof high-resistance material having portions of the plane surface thereof of higher resistance than the body portion.

24. A space-current discharge device comprising electrode plates contacting at only a relatively small number of points, the

remaining portions of the contact surfaces being spaced, at least one of said plates being a plane plate of high-resistance material having a face thereof of higher resistance than the body portion.

25. A space-current discharge device comprising electrode plates contacting at only a relatively small numberof points, the remaining portions of the contact surfaces being spaced, at least one of said plates being a plane plate of high-resistance material having the opposite faces thereof of higher resistance than the body portion.

26. A space-current discharge device comprising electrode plates contacting at only a relatively small number of points, the

remaining portions of the contact surfaces being spaced, at least one of said plates being a plane plate of high-reslstance material having portions of the plane surface thereof of higher resistance than the body portion, the spacing and resistivity being such that the space current flow always takes the form of a glow-discharge.

27. A space-current discharge device comprising electrode plates contacting at only a relatively small number ofpoints, the remaining portions of the contact surfaces being spaced, at least one of said plates being a plane plate of high-resistance materialhaving portions of the plane surface thereof of higher resistance than the body portion, the spacing and resistivity being such that the space current flow always takes higher resistance than the body portion, the 10 the form of a glow-discharge. spacing and resistivity being such that the 28. A space-current discharge device comspace current flow always takes the form prising electrode plates contacting at only of a glow-discharge.

a relatively small number of points, the In testimony whereof, I have hereunto remaining portions of the contact surfaces subscribed my name this 29th day of 15 being spaced, at least one of said plates March, 1922. being a plane plate of high-resistance material having the opposite faces thereof of J OSEPH SLEPIAN. 

